How do I make the Copy To/Append To mailbox menus smaller?
Open the Preferences dialog from the File menu.
Make sure it is set to Advanced (use the radio buttons on the right hand side).
Switch to the Mailbox panel.
Switch to the Advanced panel in the Mailbox panel.
Turn on the "Use 'Copy Messages To' Cabinet" and "Use 'Copy Drafts To' Cabinet" checkboxes.
Exit the preferences dialog by clicking OK.
In the server window (the one showing the list of mailboxes) click on the Cabinet and select the 'Copy Messages To' item if its not already checked.
Do the same for the 'Copy Drafts To' item in the Cabinet popup.
You will now see these two Cabinet items appear in the top-part of the server window.
Select the mailboxes you frequently use for copying incoming messages to and drag and drop them on thre 'Copy Messages To' cabinet item.
Do the same for mailboxes you copy drafts into but drop them on the 'Copy Drafts To' cabinet.
Hide the two cabinet items by selecting each in turn from the Cabinet popup.
Now the Copy To mailbox popups will just show the mailboxes added to the corresponding cabinet items. There will also be a list of other mailboxes that were recently used below those (the maximum number of which is set in the preferences). You can still copy to any mailbox by using the Choose option in the popup which will display a mailbox browser dialog allowing you to pick the mailbox you want.